The present invention relates to a process for extracting the unsaponifiable components of vegetable oils and to pharmaceutical or cosmetic compositions containing the unsaponifiable components thus obtained, and to the use of these compounds for the manufacture of a medicament, in a method of cosmetic treatment and as a food additive.
Unsaponifiable compounds constitute the fraction of a fatty substance which, after prolonged action of an alkaline base, remains insoluble in water and can be extracted with an organic solvent.
Five main groups of substances are present in most unsaponifiable components of vegetable oils: saturated or unsaturated hydrocarbons, aliphatic or terpenic alcohols, sterols, tocopherols and carotenoid and xanthophilic pigments.
Unsaponifiable compounds are sought after for their pharmacological, cosmetic and nutritional properties.
The usual processes for producing unsaponifiable components of vegetable oils comprise a step of saponification of the fats and extraction of the target products (the unsaponifiable component) with an organic solvent. Generally, the solvents most commonly used are solvents for oils, such as alkanes (hexane, heptane and the like) and chlorinated solvents (dichloroethane, trichloroethane, carbon tetrachloride and the like).
Among the latter, dichloroethane constitutes the best candidate by virtue of its effective extraction yield and its intrinsic selectivity. The unsaponifiable components are indeed composed of numerous substituents which need to be extracted completely and with a maximum yield.
However, from the industrial point of view, the toxicity of the solvent used as well as its chemical stability must be taken into account. In this regard, dichloroethane (DCE) has two major disadvantages: DCE is indeed classified among the most toxic solvents, and has, moreover, a detrimental impact on the environment. In addition, DCE is partially degraded in basic medium (case of soapy saponification solutions).
The problem posed by the present invention is to choose an extraction solvent which is less toxic and chemically more stable than dichloroethane and which makes it possible to extract the unsaponifiable components with a yield and a selectivity which are at least comparable to the yields and selectivities obtained using dichioroethane, it being possible for this solvent also to be used in a crystallization process.
The subject of the present invention is thus a process for extracting the unsaponifiable fraction contained in a vegetable oil or of a coproduct of the vegetable oil refining industry such as the unchanged materials from deodorization, comprising at least:
A) a step during which the said oil is converted to an aqueous-alcoholic solution which is preferably a step chosen from the group consisting of saponifications and esterifications,
B) a step of extraction of the aqueous-alcoholic solution during which the fatty fraction is separated from the unsaponifiable fraction chosen from the group consisting of liquid-liquid extractions and distillations,
C) optionally, a step of purification of the unsaponifiable component chosen from the group consisting of crystallizations and liquid-liquid extractions, such as at least one step among the liquid-liquid extractions of step B, the crystallizations of step C or the liquid-liquid extractions of step C is carried out using 1-chlorobutane.
The process according to the present invention makes it possible to extract an unsaponifiable fraction contained in a vegetable oil; it also makes it possible to extract a coproduct of the vegetable oil refining industry, such as for example the unchanged materials from deodorization, also called deodistillates, which are produced during the refining of vegetable oils.
The fatty acids and the partial glycerides present in the deodistillates may indeed be saponified or esterified with a light alcohol, with the aim of separating the fatty fraction from the unsaponifiable fraction, either by liquid-liquid extraction or vacuum distillation. Finally, the purification of the unsaponifiable component or of the active fractions separated, most often the tocopherols (vitamin E) and the sterols, involves in particular steps of crystallization from an organic solvent or of liquid-liquid extraction.
The subject of the present invention is also a process for extracting the unsaponifiable fraction contained in a vegetable oil, comprising at least:
A) a saponification step by which the said oil is converted to an aqueous-alcoholic solution,
B) a step of extraction of the aqueous-alcoholic solution with an organic solvent such that the organic solvent is 1-chlorobutane; preferably, the vegetable oil treated is an avocado oil or soybean oil.
More particularly, the process for extracting the unsaponifiable fraction of an avocado oil according to the present invention is such that a countercurrent extraction of the aqueous-alcoholic solution is carried out by means of 1-chlorobutane, the (volume/volume) v/v 1-chlorobutane/aqueous-alcoholic solution ratio being between 0.5 and 5, preferably between 0.9 and 1.2 and more preferably still about 1.
More particularly, the process for extracting the unsaponifiable fraction of a soybean oil according to the present invention is such that a countercurrent extraction of the aqueous-alcoholic solution is carried out by means of 1-chlorobutane, the (volume/volume) v/v 1-chlorobutane/aqueous-alcoholic solution ratio being between 0.5 and 5, preferably between 0.9 and 1.5 and more preferably still about 1.3.
The subject of the present invention is also a process for extracting the unsaponifiable fraction of a coproduct of the vegetable oil refining industry, such that this coproduct is a deodistillate of a vegetable oil, the said process comprising at least:
a saponification step by which the deodistillate is converted to an aqueous-alcoholic solution,
a step of countercurrent extraction of the aqueous-alcoholic solution by means of 1-chlorobutane,
a step of crystallization of the sterols and/or of the triterpenic alcohols,
a step of isolation of an active compound such as tocopherols, tocotrienols, squalene, carotenes, sesamin or sesamolin, which step is chosen from the group consisting of extractions, preferably by means of 1-chlorobutane, and distillations.
The subject of the present invention is also the unsaponifiable fraction obtained by the extraction process according to the present invention.
Comparison of the contents of unsaponifiable components of various vegetable oils: soybean, cotton, coconut, olive and avocado, shows that the avocado oil obtained by extraction according to various known processes comprises a particularly high level of unsaponifiable components. Typically, the contents obtained range from 2 to 7% of unsaponifiable components in avocado oil against 0.5% in coconut oil, 1% in soybean oil, 1% in olive oil. The unsaponifiable component of avocado may be prepared by extraction from avocado oil.
The process for extracting the unsaponifiable components of an avocado oil may be carried out in the following manner.
According to a method known to persons skilled in the art:
either the fresh pulp is pressed in the presence of a third fibrous substance absorbing water such as coffee parchment in a cage press, and then the emulsion of oil and water obtained is separated by decantation and/or centrifugation;
or the fresh pulp is ground and brought into contact with a suitable organic solvent (for example a methanol-chloroform mixture) and then the oil is recovered by evaporation of the solvent.
Several processes have been described in the prior art for extracting the unsaponifiable fraction of a vegetable oil.
There may be mentioned in particular the process for preparing the unsaponifiable component of avocado oil as described and claimed in patent FR-2,678,632 in the name of Pharmascience Laboratories. This process makes it possible to obtain an unsaponifiable component of avocado rich in fraction H by comparison with the conventional processes for preparing the unsaponifiable component of avocado.
Thus, the unsaponifiable component of avocado oil used according to the invention may be obtained from fresh fruit but, preferably, the unsaponifiable component of avocado is prepared from fruit which has been previously heat-treated before the extraction of the oil and the saponification, as described in patent FR-2,678,632. This heat treatment consists in a controlled drying of the fruit, preferably fresh fruit, for at least four hours, advantageously at least 10 hours, preferably between about 24 and about 48 hours, at a temperature preferably of at least about 80xc2x0 C. and preferably between 80 and about 120xc2x0 C.
There may also be mentioned the process for preparing the unsaponifiable component of soybean oil, obtained from an unsaponifiable concentrate of soybean oil. The said unsaponifiable concentrate is prepared by molecular distillation according to a process as described for lupin oil in patent application FR-2,762,512, but adapted for soybean oil. In this process, the soybean oil is distilled in a molecular distillation apparatus of the centrifugal or scraped-film type, at a temperature of between about 210 and 250xc2x0 C. and under a high vacuum of between 0.01 and 0.001 millimetres of mercury (that is 0.13 to 1.3 Pa). The distillate obtained has a content of unsaponifiable component of between 5 and 40% by weight and therefore constitutes an unsaponifiable concentrate of soybean oil.
The concentrate is then saponified with a base such as potassium hydroxide or sodium hydroxide in an alcoholic, preferably ethanolic, medium. It is then subjected to one or more extractions with 1-chlorobutane.
The extraction solution obtained is then preferably centrifuged, filtered and then washed with water in order to remove residual traces of alkalinity.
The extraction solvent is carefully evaporated in order to recover the unsaponifiable component. It is of course also possible to envisage additional operations known to persons skilled in the art, such as a deodorization step.
Finally, before its saponification, oil may be enriched beforehand in unsaponifiable component by separating a majority of the constituents from the unsaponifiable component which is recovered in a concentrate. Various methods can be used: cold crystallization, liquid-liquid extraction, molecular distillation.
The preliminary concentration of the oil in unsaponifiable component makes it possible to reduce the consumption of oil during the saponification. Molecular distillation is particularly preferred, being preferably carried out at a temperature of between about 180 and about 230xc2x0 C., while a pressure of between 10xe2x88x923 and 10xe2x88x922 mmHg, and preferably of the order of 10xe2x88x923 mmHg, is maintained. The concentration of unsaponifiable components of the distillate may be up to 60%.
The subject of the present invention is also a cosmetic composition comprising at least one unsaponifiable fraction contained in a vegetable oil and a cosmetically acceptable excipient, a pharmaceutical composition or a composition as a medicament comprising at least one unsaponifiable fraction contained in a vegetable oil and a pharmaceutically acceptable excipient and a dietary composition comprising at least one unsaponifiable fraction contained in a vegetable oil.
The present invention also relates to a process of cosmetic treatment such that the cosmetic composition according to the invention is applied topically and also to the use of an unsaponifiable component of a vegetable oil obtained according to the present invention for the manufacture of a medicament.
By way of examples illustrating the present invention, two series of experiments were successively carried out.